Superwarfarins are long-acting anticoagulants (half life 24 days or more) with a potency much greater than that of warfarin. They are widely available in rodenticides and may be ingested intentionally or accidentally. Because of the long half-life and potency of the compounds, bleeding may be severe and therapy may need to be given for a prolonged period.


Chemical types of superwarfarins:

(1) hydroxy coumarin derivatives with a 4-bromo-(1-1 biphenyl) side chain

(2) coumatetryls

(3) indanediones


Exposure situations:

(1) accidental ingestion by small children

(2) suicide attempt

(3) Munchausen's syndrome

(4) psychosis or other mental illness


Clinical findings:

(1) bleeding and/or bruising

(2) negative history for coumadin therapy

(3) negative for inhibitor

(4) resistance to vitamin K1 administration (not reversed by usual therapeutic doses)


Laboratory findings:

(1) prolonged PT and PTT

(2) decreased levels of Factors 2, 7, 9 and 10 with normal levels of Factor 5 (Factor 5 is not vitamin K dependent and a depressed Factor 5 might indicate DIC or liver disease)

(3) increased ratio of vitamin K1 epoxide to reduced vitamin K1

(4) presence of superwarfarin in blood



(1) Vitamin K1 administration, sometimes requiring repeated and continuous administrations for weeks or months.

(2) Bleeding may require transfusion of fresh frozen plasma (FFP).

(3) The identification of how ingested with steps to prevent future exposure.


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